PASADENA, Calif.--At the 50th anniversary space conference here Thursday, a fight over the future role of NASA's space program inadvertently took off.

If it were up to Burt Rutan, the aerospace engineer known for building a suborbital rocket plane that won the Ansari X Prize, NASA wouldn't be developing a spacecraft to put another man on the moon by 2020. That government mission has already been accomplished, and a repeat performance is "silly," Rutan said during a panel held at California Institute of Technology, CalTech, which runs NASA's Jet Propulsion Lab.

"Taxpayer-funded NASA should only fund research and not development," Rutan said. "When you spend hundreds of billions of dollars to build a manned spacecraft, you're...dumbing down a generation of new, young engineers (by telling them) 'No, you can't take new approaches, you have to use this old technology.'"

"I think it's absurd they're doing Orion development at all. It should be done commercially," he said, referring to the name of the lunar spacecraft. Rutan and other panelists also question the importance of space flight at a time when environmental concerns are paramount.

NASA Administrator Michael Griffin responded to Rutan's vision in a speech following his panel. "Unlike Rutan, I will continue to think space programs are important," Griffin said.

Of course, Rutan has a big stake in commercial development of spacecraft. As founder and president of Scaled Composites, he develops rockets for future commercial space tourism. Rutan is among a cadre of technology entrepreneurs, including Amazon founder Jeff Bezos, Paypal co-founder Elon Musk and Virgin CEO Richard Branson, who are working on ventures to send people into space.

Rutan designed SpaceShipOne, the rocket that won the $10 million Ansari X Prize by breaking the Earth's atmosphere twice during a set time. And his company is building SpaceShipTwo for Branson's Virgin Galactic, which aims to launch its first commercial flight in 2009. But Scaled Composites recently suffered a tragedy when two people were killed in an explosion at the company's facility in Mojave, Calif.

In his speech, Griffin talked about NASA's budget for the last 50 years, adjusted for inflation. He said that the most money NASA has ever received from the government was not the period during the Apollo missions, but over the 10 years from 1989 to 1998. "So we get more money today than (what was) given the agency during Apollo" (during the 1960s and 1970s). NASA's budget for 2007 is $14 billion, or about 15 cents a day of a taxpayer's money, according to Griffin.

Part of Rutan's argument against NASA's development program was that after the early 1970s, when astronaut Alan Shepard golfed on the moon, there wasn't "much innovation."

Griffin didn't respond directly to whether or not there is a lack of innovation. But in response to criticism on an earlier panel that NASA's science budget has waned, he said the first decade of NASA's budget was proportionally the same as its most recent budget. During the first 10 years of the space agency, he further clarified, 58 percent of its budget was devoted to human spaceflight, 17 percent to science, 6 percent to aerospace and 10 percent to new technologies. In contrast, in 2006, 62 percent of NASA's budget was earmarked for spaceflight and 32 percent was for space science, he said. Last year, NASA didn't have a budget to develop new technologies.

"There is a mythology that science has been decimated by human spaceflight. That's not right." Griffin said.

He added that the current missions back to the moon and onto Mars by 2035 are sustainable programs, ones that wouldn't likely be stemmed by a change in administrations.

"We have here a program which is affordable, sustainable and which can be highly correlated to historical successes and developments from the past," said Griffin.

Rutan said that the goal of private space tourism is to reduce the cost of space travel and exploration. "If we go through a time period where the focus is on flying the consumer, these 'payloads' who pay to fly and can be reproduced with unskilled labor...with tools around the house," he joked, "there will be a breakthrough to enormous volume."